Core C provides the instruments, techniques, personnel and expertise necessary for in vivo quantification of the distribution of radioactivity in large animals and human beings. This Core has three main types of activities: supervision of the performance of scans, development and implementation of new acquisition and image processing techniques, and collaboration with each Project in the optimization of acquisition and processing protocols. This Core contains the instrumentation, image processing workstations, techniques for data acquisition and processing, and the personnel responsible for the Core's operation.